| 摘要 |
The invention provides a transmission fluid composition which has a kinematic viscosity as determined at 100°C of 2 to 10 mm 2 /s and a viscosity index of 150 or higher and which satisfies a relationship between kinematic viscosity and NOACK evaporation loss amount represented by formula (I): X / 3 + Y ‰ 6.33
(wherein X represents a kinematic viscosity (mm 2 /s) as determined at 100°C, and Y represents a NOACK evaporation loss amount (mass%) at 200°C for one hour), and a transmission fluid composition containing, as a base oil, at least one species selected from among ±-olefin oligomers produced through oligomerization of an ±-olefin through a specific method and hydrogenation products of the oligomers. Such transmission fluid compositions exhibit a very small evaporation loss despite having low viscosity, and a long metal fatigue life (e.g., pitting resistance) and have high viscosity index, good low-temperature fluidity, good extreme pressure properties, and good oxidation stability, and are suitable for transmissions, particularly automatic transmissions. |
